How Worms Find Food and Avoid Toxins Using G Protein-Coupled Receptors to Detect Volatile Chemicals: Testing for Hexane with Caenorhabditis elegans. Hagop Toghramadjian, Sarah Hays
The purpose of this lab was to test the chemotaxis response of the nematode worm C. elegans to previously identified attractants and repellants. Once the assay was established, the next step was to test chemotaxis response to a potential soil toxin. To accomplish this task, wild-type and mutant strains of C. elegans were obtained from the stock center at the University of Minnesota. Adult worms were isolated and placed onto chemotaxis assay plates. The volatile odorants were dissolved in ethanol and placed at one end of the plate, and a control drop of ethanol was placed on the opposite side. C. elegans were allowed to chemotax for 2-3 hours and then their relative movement towards or away from the volatile odorant was recorded. Wild-type and mutant C. elegans differed in their chemotaxis response to the previously characterized odorants. In addition, an attraction to the potential soil toxin hexane, was observed. In phase two, the concentration of hexane was varied in order to observe the C. elegans response to increased concentration. When matched with the isoamyl alcohol, acetone and octanol models, C.elegans' response to hexane indicated repulsion, though response varied for different types of the worm. Caenorhabditis elegans’ apparent repulsion from hexane may prove very useful in testing for the pollutant, especially because the worm can detect very low concentrations.
Liao, C., Gock, A., Michie, M., Morton, B., Anderson, A., & Trowell, S. (2010). Behavioural and Genetic Evidence for C. elegans' Ability to Detect Volatile Chemicals Associated with Explosives PLoS ONE, 5 (9) DOI: 10.1371/journal.pone.0012615
Hofler C. & Koelle M. R. (2011). AGS-3 and RIC-8 Activate Gαo during Food Deprivation. The Journal of Neuroscience, 31, 11553-11562.
Shields, J.D. (2007). Autologous Chemotaxis as a Mechanism of Tumor Cell Homing to Lymphatics via Interstitial Flow and Autocrine CCR7 Signaling. Cancer Cell, 11, 526538.
Schmitz, C., Kinge, P. & Hutter, H. (2007) Axon Guidance Genes Identified in a Large-Scale RNAi screen using the RNAi-hypersensitive Caenorhabditis elegans strains nre 1(hdR20)lin-15b(hd126). Proceedings of the National Academy of Sciences, 104, 834 839
Terrill, W. F. & Dusenbery, D. B. (1996). Threshold Chemosensitivity and Hypothetical Chemoreceptor Function of the nematode Caenorhabditis elegans. Journal of Chemical Ecology, 22, 1463-1475
How Worms Find Food and Avoid Toxins Using G Protein-Coupled Receptors to Detect Volatile Chemicals: Testing for Hexane with Caenorhabditis elegans. Hagop Toghramadjian, Sarah Hays
The purpose of this lab was to test the chemotaxis response of the nematode worm C. elegans to previously identified attractants and repellants. Once the assay was established, the next step was to test chemotaxis response to a potential soil toxin. To accomplish this task, wild-type and mutant strains of C. elegans were obtained from the stock center at the University of Minnesota. Adult worms were isolated and placed onto chemotaxis assay plates. The volatile odorants were dissolved in ethanol and placed at one end of the plate, and a control drop of ethanol was placed on the opposite side. C. elegans were allowed to chemotax for 2-3 hours and then their relative movement towards or away from the volatile odorant was recorded. Wild-type and mutant C. elegans differed in their chemotaxis response to the previously characterized odorants. In addition, an attraction to the potential soil toxin hexane, was observed. In phase two, the concentration of hexane was varied in order to observe the C. elegans response to increased concentration. When matched with the isoamyl alcohol, acetone and octanol models, C.elegans' response to hexane indicated repulsion, though response varied for different types of the worm. Caenorhabditis elegans’ apparent repulsion from hexane may prove very useful in testing for the pollutant, especially because the worm can detect very low concentrations.
Keywords: Caenorhabditis elegans, hexane, isoamyl alcohol, acetone, octanol, gasoline pollution, chemotaxis, attraction, indifference, repulsion, wild type
apparatus:
http://www.etsy.com/listing/88344894/mediterranean-dreams-adjustable-ring?ref=sr_gallery_5&ga_search_submit=&ga_search_query=rings&ga_order=most_relevant&ga_ship_to=US&ga_view_type=gallery&ga_page=3&ga_search_type=handmade&ga_facet=handmade
Figure 1: Pipetting the worms onto the chemotaxis plate
Summary Graphic
Key Sources:
Bargmann, C. (2006). Chemosensation in C. elegans . WormBook. Retrieved February 16, 2012, fromhttp://www.wormbook.org/chapters/www_chemosensation/chemosensation.html#sec1_3
Liao, C., Gock, A., Michie, M., Morton, B., Anderson, A., & Trowell, S. (2010). Behavioural and Genetic Evidence for C. elegans' Ability to Detect Volatile Chemicals Associated with Explosives PLoS ONE, 5 (9) DOI: 10.1371/journal.pone.0012615
Hofler C. & Koelle M. R. (2011). AGS-3 and RIC-8 Activate Gαo during Food Deprivation. The Journal of Neuroscience, 31, 11553-11562.
Shields, J.D. (2007). Autologous Chemotaxis as a Mechanism of Tumor Cell Homing to Lymphatics via Interstitial Flow and Autocrine CCR7 Signaling. Cancer Cell, 11, 526538.
Schmitz, C., Kinge, P. & Hutter, H. (2007) Axon Guidance Genes Identified in a Large-Scale RNAi screen using the RNAi-hypersensitive Caenorhabditis elegans strains nre 1(hdR20)lin-15b(hd126). Proceedings of the National Academy of Sciences, 104, 834 839
Terrill, W. F. & Dusenbery, D. B. (1996). Threshold Chemosensitivity and Hypothetical Chemoreceptor Function of the nematode Caenorhabditis elegans. Journal of Chemical Ecology, 22, 1463-1475
Titus, M, personal communication, January 7, 2012